How can I find what stock I have?

You're going to find the paper work or at the least, find the name of the firm that your grandfather used to buy the sock - there should have been monthly or at least quarterly statements sent.

The firm that is holding the stock does send out statements- so you're going have to find the name of the firm.

Once you find the brokerage firm, you will need to contact them and they will provide you a list of the paper work you will need to change the registration of the securities.

You will need your grandfather's tax id, along with your grandmother's since she would have been the survivor of your grandfather's estate.

You could contact the Secretary of State where you grandfather lived in the event that the property was escheated to the state for failure to be able to contact you grandfather.If the assets were sent to the state, you can retrieve them but you will have to provide proof of relationship etc, but the state office can provide you all that you will need

Other than above, there is no way any one can find you. There's about 35,000 brokerage firm here in the US where you grandfather may have opened the account.

Ask your mom who was in charge of her estate.

Note that money in accounts has to be used to pay off debt a person may leave behind.

That money could be long, long gone.